The best replacement for tau is eldar.

The best alternatives to tau are rated as following:
★★★★★  eldar
★★★★★  pi
★★★★★  necrons
★★★★  space marines
★★★  orks
★★  imperial guard
★★  tyranids
★★  chaos
★★  dark eldar
★  necron
★  eldar tactics
★  imperium
★  pi numberphile
★  protoss
★  grey knights
★  tyranid
  white scars
  space wolves
  dark angels
  sony wega
  space marines tactics
  ig
  tyranids tactics
  akrho
  spearman
  space marine
  nids
  necron tactics
  spearman rank
  blood angels
  wega

Your alternative for tau is not listed? Suggest!
Speaking about tau, one probably shouldn't forget about necrons.

Other search terms related to tau and their ratings are:
★★★★★ necrons
★★★ smac
★★ space marines
You have in mind a companion for tau and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of tau in all years. Click on graph for more.
tau
eldar
pi